Appliance devices such as dishwashers, clothing washing machines, dryers, ovens, refrigerators and the like often include electrical control circuits. Such control circuits receive input from the user and control the operation of the appliance device based on the received input. In many cases, the overall operation of the appliance is predefined as a general matter and the user input merely modifies the predefined operation in some way.
For example, the operation of a dishwasher typically involves the processes of filling, washing, draining and rinsing. Such operations involve, among other things, the control of water valves, detergent valves and motor relays. The general sequence of such operations is generally predefined. However, user input may be used to alter the sequence, or to define certain parameters of the sequence. For example, the user input may define whether the wash cycle is normal, light, or heavy. Although the general sequence does not necessarily change dependent upon wash cycle selection, the length of certain processes within the sequence does change.
A typical user input interface for a dishwasher includes a rotary knob and a plurality of pushbutton switches. The rotary knob is attached to a cam that controls the sequence of operations within the dishwasher. The cam has a number of followers that trigger the operation of the various dishwasher components. The cam followers are positioned to cause various operations to be executed in a “programmed” sequence. The user selects a particular cycle by rotating the knob to particular position associated with the selected cycle. Upon actuation, the cam begins to rotate automatically started from the user selected position, performing each operation as defined on the cam “program” from the user-selected point forward. The pushbutton switches are used to activate/deactivate various options that are not available through the cam program. For example, pushbutton switches may be used to selectively activate a heated dry cycle, a delayed start, or a high temperature wash.
More recently, electronic controllers, for example, microprocessors and microcontrollers, have replaced the rotary cam control device. The use of electronic controllers provides flexibility and features not typically available in cam control devices. Moreover, as a general matter, replacement of moving parts, such as electromechanical rotating cams, typically increases reliability in products.
However, the use of electronic controllers has added to the complexity of servicing appliances. Small electronic integrated circuits do not lend themselves to the methods of troubleshooting and repair that have historically been used with mechanical and electromechanical devices. Accordingly, malfunctions in an electronically controlled appliance are more difficult to diagnose and resolve than those of the old, mechanical cam controlled devices.
U.S. patent application Ser. No. 10/264,888, assigned to the assignee of the present invention, discloses a diagnostics tool that utilizes an optical transmitter and an optical receiver in a communication probe for bi-directional communication with an appliance controller through an indicator light of the appliance control panel and an optical detector on an external panel of the appliance. The ability to obtain data information from an electronic controller may be used to obtain diagnostic, operational, or test data from the controller regarding the operation of the appliance.
The optical communication probe may be powered directly from the diagnostic tool or it may be powered by a battery. Battery power may be preferred when the diagnostic tool and communication probe are used in service calls. In this type of transportable use, the user prefers not to need to find a power outlet in the room or facility were an appliance being serviced may be located in order to operate the diagnostic tool or its communication probe. To address the need for battery power for the probe, the battery source for the diagnostic tool may be accessed or the communication probe may be provided with its own battery. Coupling the communication probe to the diagnostic tool battery power is not favored because the drain of both the diagnostic tool and the communication probe on the diagnostic tool battery may substantially reduce its life. However, providing a separate battery for the communication probe still presents the issue of how to extend the life of the battery for the communication probe because a user does not want to carry a large supply of batteries so discharged batteries may be replaced during or between service calls. Furthermore, the interval between service call uses may not be sufficient to recharge one or more batteries from a re-charger that may be located in a service truck or the like. If a timer is placed on the communication probe battery then it needs to be coordinated with the diagnostic tool so the tool knows when the probe is powered for communication and the complexity of the probe electronics is increased. Likewise, if the communication probe battery shuts down for lack of activity at the probe, the diagnostic tool may attempt to communicate through a probe that is not being powered. Therefore, a need exists for extending the life of a separate battery that is being used to supply electrical power to a communication probe coupled to a diagnostic tool without unnecessarily increasing the complexity of the probe electronics.